1. Field of the Invention
The present invention relates to downhole oil and gas well tools and particularly to an improved junk bailer apparatus that can remove debris and/or "junk" from a well bore. Even more particularly, the present invention relates to an improved "junk" bailer apparatus that features a reciprocating pumping action combined with catch fingers and flexible brush "escalator" members to pump debris into a tool body cavity and then hold the debris or junk within the cavity using the catch fingers. In one embodiment, magnetic members and multiple sets of fingers define an "escalator" that gradually intakes debris and transports it farther and farther into the tool body cavity. Staging magnets are attached to the body of the tool and are exposed to the lower chamber by a slot in the lower piston. The flexible fingers or brushes move the debris from magnet to magnet in stages, finally reaching a storage area.
2. General Background of the Invention
Various "junk" bailers are commercially available for removing debris or junk from an oil and gas well bore. Some of these prior art bailers use a venturi-type pumping arrangement that is often inefficient. Other bailers use hydrostatic pressure to force "junk" or debris into a tool housing when a valve is opened or a disk is ruptured after the tool is placed downhole.
In prior U.S. Pat. No. 3,946,819, naming the applicant herein as patentee, there is disclosed a fluid operated well tool adapted to deliver downward jarring forces when the tool encounters obstructions. The tool of my prior U.S. Pat. No. 3,946,819, generally includes a housing with a tubular stem member telescopically received in the housing for relative reciprocal movement between a first terminal position and a second terminal position in response to fluid pressure in the housing. The lower portion of the housing is formed to define a downwardly facing hammer and the stem member includes an upwardly facing anvil which is positioned to be struck by the hammer. The tool includes a valve assembly that is responsive to predetermined movement of the stem member toward the second terminal position to relieve fluid pressure and permit the stem member to return to the first terminal position. When the valve assembly relieves fluid pressure, the hammer moves into abrupt striking contact with the anvil.
In prior U.S. Pat. No. 4,462,471, naming the applicant herein as patentee, there is provided a bidirectional fluid operated jarring apparatus that produces jarring forces in either the upward or downward direction. The jarring apparatus was used to provide upward or downward impact forces as desired downhole without removing the tool from the well bore for modification. The device provides downward jarring forces when the tool is in compression, as when pipe weight is being applied downwardly on the tool, and produces strong upward forces when is in tension, as when the tool is being pulled upwardly.
In the '471 patent, there is disclosed a jarring or drilling mechanism that may be adapted to provide upward and downward blows. The mechanism of the '471 patent includes a housing having opposed axially spaced apart hammer surfaces slidingly mounted within the housing between the anvil surfaces. A spring is provided for urging the hammer upwardly.